Field of the Invention
The present invention relates to an improvement for metal golf club heads.
b) Description of the Prior Art
Recently, golf clubs which were originally called "wood clubs" have been developed in which the golf club head comprises a synthetic resin foam core material surrounded by an outer shell. For example, it is known to use a carbon fiber reinforced resin layer which is compression molded onto the surface of the core material. It is also known to form an outer shell from materials such as stainless steel, titanium and fiber reinforced metallic composites. The advantages of artificial "wood" club heads over natural "wood" club heads, traditionally milled from persimmon or cherry wood, are uniformity of construction and consistency of performance.
Generally, golf club heads with a metal outer shell provide an unpleasant, "hard" feeling when hitting a golf ball. FIG. 5 shows the golf club head disclosed in Japanese Examined Utility Model Publication No. Hei. 2-29973 which recognizes this problem. This reference suggests making the ball hitting surface 3 more elastic with respect to the metal outer shell 1 using reduced cross-section portions 7 around the face plate 5. The disadvantage being the stresses due to impact with the ball are concentrated in the reduced cross-section portions 7, potentially resulting in damage or failure over a long period of use.
Japanese Unexamined Patent Publication No. Hei. 1-259876 suggests further increasing the elasticity of metal golf club heads by the attachment of face member 15 to the outer shell 9. Specifically, the face member 15, made of fiber reinforced plastic in the reference, is attached to face portion 11 of exterior recess 13 formed in the outer shell 9. However, adequate elasticity is achieved only in the proximity of where the recess 13 connects with the V-shaped portion of the outer shell 9, i.e. near the upper portion of the shell 9 as shown in FIG. 6. The remaining portions of the face member provide substantially less elasticity.